General Lab Information

Energy Systems Division

Geothermal Materials Group

CO2- as a working fluid

Based on the excellent heat transport properties of supercritical carbon dioxide (scCO2) compared with that of water, scCO2 is very attractive for use as a geo-working fluid in Enhanced Geothermal Systems (EGS). However, one serious concern raised for scCO2 geofluid is its reactivity with rock formations, causing the wet carbonate erosion of rocks, particularly granite, known to be the major rock in EGS well formations. BNL research helped improve the understanding of carbonation kinetics and mechanisms of three-type of granites containing different minerals, as well as many other rocks and clays present in well formations as a function of temperature up to 250oC and pressure up to 2000 psi. The research results provided information on the erosion rates of granite rocks within 10 years, as well as phase identification and classification of minerals in rocks with high and low erosion rates.